<!DOCTYPE html>
<html lang="zh_CN">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <h2>我是 <font color="red">标签</font></h2>
    <!--上面是合法的-->

    <!--下面是错误，标签只能是层级嵌套，不能相互嵌套-->
    <!--<h2>我是 <font color="red">标签</h2></font>-->
</body>
<script type="text/javascript">

</script>

</html>
